We present the results of CO interferometric observations of the southern elliptical galaxy NGC 3557 with ALMA .
We have detected both the CO ( 1-0 ) emission line and a relatively strong continuum at 3mm .
The continuum shows a flat-spectrum central unresolved source ( at our angular resolution of 0 \farcs 7 ) and two jets , associated with the larger scale emission observed at lower frequencies .
The molecular gas in NGC 3557 appears to be concentrated within 250 pc of the center , and shows evidence of organized rotation along the same axis as the stellar component and the symmetry axis of the nuclear dust absorption reported in the literature .
We obtained M _ { H _ { 2 } } = ( 9.0 \pm 2.0 ) x10 ^ { 7 } M _ { \odot } of molecular gas , which has an average CO ( 2-1 ) to CO ( 1-0 ) line ratio of 0.7 , which is relatively high when compared with the values reported in the literature for bona-fide ellipticals observed with single-dish telescopes .
NGC 3557 shows further a high excitation peak ( i.e. , CO ( 2-1 ) /CO ( 1-0 ) \approx 1.1 \pm 0.3 offset 0 \farcs 7 from the center , which appears to be associated with a region of higher velocity dispersion that does not share the overall rotation pattern of the molecular gas , but aligned with the radio jet .
The molecular gas disk in this object appears to be stable to local gravitational instabilities .